Narrow or wide beam

[apcsilver]

On a rib of approx 8 meter could anyone advise on the merits of a wide or narrow beam boat. My understanding is that a narrower beam will generally mean the boat is more seaworthy in rougher seas which would be my priority over any extra space afforded by a wider beam

[Pikey Dave]

Originally Posted by apcsilver

On a rib of approx 8 meter could anyone advise on the merits of a wide or narrow beam boat. My understanding is that a narrower beam will generally mean the boat is more seaworthy in rougher seas which would be my priority over any extra space afforded by a wider beam

Depends on your definitions of wide & narrow. An 8m RIB would typically have a 2.7m beam. Long narrow beam boats (Humber Attaque?) are more likely to “Stuff” in a following sea due to lack of lateral buoyancy. Think: it’s easier to push something sharp & pointy into an object (wave) than something broad & blunt.
The boat’s length & width need to be in proportion. If I had the choice of an 8m RIB in either 2.9m/2.7m or 2.4m beam, I’d choose the 2.9m. I’d be confident that all things being equal, this would be the better sea boat.

[Maximus]

Originally Posted by apcsilver

On a rib of approx 8 meter could anyone advise on the merits of a wide or narrow beam boat. My understanding is that a narrower beam will generally mean the boat is more seaworthy in rougher seas which would be my priority over any extra space afforded by a wider beam

Probably the other way round
It's obviously a matter of degrees....but Viking "Longships".....were pretty Beamy...and didn't stop them stretching thier Legs
The Keel/Hull on most RIBs is narrow regardless ....generally with a Deep V and high dead rise to help cut though the chop and help "plant" the Boat in the waves whilst manovering..add inflatable Tubes and a RIB out performs most other water craft for thier size.
As for Beam ...Narrow Boat "Speed Needle" type will often be faster in ideal conditions but overall stability especially in Rough and Confused Seas is better served by more beam and often larger Tubes ...pluss the higher overall weight in my experience.
Plenty of Power comensurate with size of RIB!...and you're good to go!
Coming from Thailand you've probably seen the large "outriggers" on traditional watercraft...not for speed but they certainly help with stability and Sea Keeping